Stencil production.



L. LEWIS.

STENCII. PRODUCTION.

APPLICATION man JUNE 3.1915.

,Patnted Apr. 8,1919.

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L. LEWIS.

STENCIL PRODUCTION.

APPLICATION FILED JuNE 3,1915.

Patented Apr. 8,1919.

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LOUIS LEWIS, 0F LONDON, ENGLAND.

STENCIL PRODUCTION.

Specication of Letters Patent.

Patented Apr. 8, 1919.

Application led June 3, 1915. Serial No. 31,978.

ToaZZ whom it 'may concern: i

Be it known that I, Louis LEWIS, a subject of His Majesty the King of England, residing at London, England, have invented certain new and useful Improvements in Stencil Productions, of which the following is a specification.

The present invention relates to the mounting and use of fwire gauze as ay rugose surface in the production of a stencil by methods similar to the trypograph method of Zucatto. On the sheet of wire gauze is laid a sheet of waxed paper, tin foil or like easily puncturable material and the writing or the drawing is executed with a style or blunt point on the puncturable material.

Thechief object of the present invention is Ato hold a wire-fabric stencil producing surface under applied tension during the making of the stencil; this, in a preferred embodiment, suchsthat a power of increasing the tension is realized for the purpose of compensating for or mitigating any eXpansionor bulging or developing looseness of the fabric which may arise in virtue of the burnishing action of the point or style, or otherwise. The sheet of wiregauze is for the pur- Y pose ofthe present invention set in a marglnall rim, which rim should be moderately rigid or rm in relation to the gauze itself, and in order to produce that even tension of the wire gauze which is so desirable in making a stencil, the framed or marginally rimmed sheet of Wire gauze is fitted or l placed 'over and on an elevated surface, then by putting downward pressure on the Inarginal rim the sheet of wire gauze is positively tensioned both ways or in respect to warp and weft wires, thus securing an avoidance of subversive drag on the stencil sheet j with consequent distortion of writing or drawing, also giving a controllable compensation for expansion or bulging due to the burnishing action of the style.

This downward pressure on the marginal rim is by a special mode of carrying out the present invention made so adjustable that increased tension can be applied as required.

The invention may conveniently and advantageously be carried into effect as hereinafter described in detail with reference to the accompanying sheets of drawings, in

,which inverted plan view respectively of parts of the device.

Figs. 8, 9 and 10 are side, plan and side views respectively of part of the tensioning means for wire-fabric. v

a designates a dual supporting and light frame or part light frame formed with a ledge b on which a removable supporting frame c is received with a fairly close fit.

If desired the frame c may be fixed to the y frame aor the frames a and 0 may be made in one piece. A frame d formed with a marginal Yrim or elevated surface e and an intermediate rim orA elevated surface f rests upon the supporting frame c and carries another frame g formed with recesses h, z', the former at the inner edge and the latter intermediate of the inner and outer edges, whereby, when the device is assembled, the rims f of the frame d will closely fit into the recesses c' of the frame g, and the recesses bound by the rims e and f of the frame Z and the recess h of the frameg will form a substantially fully walled cavity in which a rigid marginal rim y' of the wire-fabric sheet lc may be received. The rimmed wire-fabric stencil producing surface 7c rests upon an elevated transparent backing formed by two superposed glass plates Z, m, supported by the frame a.. The top edges of the side members of the frame a and the upper face of the backing Z, fml form, as shown, an elevated surface in relation to the bottom of the recesses bounded by the rims e and f.

The end members of the frame a in the depicted example are less in height than the side members and the former are ledged at a height corresponding to the height of the side members; thus whenthe' wire-fabric is stretched over the elevated surface the transparent backing will be held against any longitudinal displacement in relation to the wire-fabric by the bending over of the wirefabric at the ends of the backing.

Full protection of the original drawing n or the like from injury during copying is secured by placing the same between the two plates Z, m.

Means for applying and maintaining contact pressure between the frame g and the frame (Z so as to thereby force down the rim of the wire-fabricl and cause the latter to be stretched and held under tension may be variously effected. Simplemeans for maintaining hand applied pressure consists of a number of clamps o secured to the frame (Z or p as desired. By furnishing such clamps with movable faces adjustable yby scre'waction, the amount of the applied pressure may be varied from time to time. l

Convenient means for mechanically applying pressure and for thereafter maintaining or varying this pressure is depicted by Figs. 4f, 8, 9 and 10. As illustrated the said means is constituted by a pin projec- 1 tion p secured to the frame g against which a gradually increasing cam or wedge power is brought to force the frame g downward. The cam action which is preferred as convenient and compact in ratio to the effecr tive length of the wedge-organ, kis constituted of a disk-g revolubly screwed against avertical side of the frame d, the curvedwedge or cam-face ofv this disk, which camfacefbears against the casing, being shown by 7 Fig. 9. At s is an opening or gap by which one of the projections p on the above mentioned frame gv can readily enter into vthe disk "g, provided that the gap s, is brought to the top. On turning the disk g the pin p and the "frame g are forced down by the operation of the cam-face 1". In certain cases as where the ytracing-device is not required to also function as a duplicator, and other provision is made for holding the stencil material the pins 10 which engage in the disk g, may be directly attached to the rigid frame with which the wire gauze is margined.

By disposing a convenient number of such disks as g on the frame d, let it be supposed three on the right side and three on the left side and fitting the frame g with pins p in suitable places an easily controlled tightening of the wire gauze is realized. A tensioning device gives a power of increasing the tension of the wire-fabric 7c for the purpose of compensating for or mitigating any expansion or bulging or devel- Oping looseness of the wire-fabric which may arise by virtue of the burnishing action of the point or style, or otherwise.

It need scarcely be mentioned that the cam faces 7 of the disks g for the two sides mustbe of corresponding action or if looked at individually on the inner face the disks and the cam faces will present contrary aspects.

Having placed the drawing n or the like to be copied between the plates Z, m of the elevated backing, the wire-fabric sheet la is fitted over the backing and the rim 0f the said sheet comes to rest in the cavity formed by the elevation e of the frame d and the recess it of the frame g, a sheet of stencil material t is placed over the wirefabric lo and passes'and is held between the frames g and d. With suiicient clearance left between these two frames and between the rim y' of the wire-fabric c and the frame d, movement of the two frames toward each other on applying pressure is permitted to thereby tension the wire-fabric By proper regulation of the pressure, the tensioning of the wire-fabric can be regulated as desired. v f I In order that easy access may be had to the drawing or to facilitate the reproduction of copies from the produced stencil, it is advantageous to hinge the framek d to the frame c as illustrated at'u. vIn case of re- L production, the wire-fabric 7c is removed and the stencil material t. with the copy of the tially fiat, while the material to which the dra-wing -is to be transferredwill be placed on the plate Z so as to rest between the latter and the stencil material t. Thehinging of thecframe will in such a case permit a speedy exchange of the material to which the drawing is to .be transferred. c Y

Any suitable source of light may be arranged under the transparent backing c.y gv., a series of electric lamps when artificial light is to be used andv in such a case or 'a comparable case water or other cooling medium may be furnished for preventing. unduefheating of the .transparent backing. It may be noted here that the size of the mesh of the wire-fabric may vary according to the neness or coarseness of the printing desired Vbut it must not be so open as to allow the point or style or type to pierce orV unduly stress the material of which the stencil is made, by driving or forcing it down into or at the interstices of the fabric. Thus the wire-fabric must be of such a mesh in relation to the impression element, that -a succession of more or less ne holes are` produced in the paraffin-paper or its equivalent when writing or typing thereon while placed on the wire-fabric. In a form of the l invention found to work well a fabric of woven copper wire having 200 strands to the linear inch Was used.

What I claim and desire to secure by Letters Patent is :-d

In a stencil producing apparatus, a supporting trarne provided with a ledge located below the top of the frame, a second supporting frame mounted onl the ledge, two transparent plates supported by said rst mentioned frame, a translucent original to be copied, held between said Plates, a

sheet of wire cloth having a rigid marginal rim stretched over the upper transparent plate, a clamping frame consisting of upper and lower clamping members shaped to form a cavity forkthe rigid marginal rim and clamping means for drawing the upper and lower clamping members together to rmly clamp theY rigid marginal rim of the wire fabric therebetween.

Signed at London, England.

In testimony whereof I aix my signature.

LOUIS LEWIS.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

